•Tryptic marker peptides for barley, maize, oats, rice, rye and wheat were identified.•An HPLC-MS/MS method to detect grain proteins in meat products was developed.•Three production series of ...sausages (grain protein: 0 and 5–1000 ppm) were produced.•LODs of ≤5 mg or ≤10 mg grain protein per kg emulsion-type sausage were determined.•The type of canning process influenced the detectability of the marker peptides.
The use of grain proteins in various types of meat products is common practice. A reliable detection of these food ingredients is required to control specifications and regarding food fraud and allergenic potential. Consequently, a sensitive HPLC-MS/MS method for the simultaneous detection of barley, maize, oats, rice, rye and wheat proteins in meat products was developed. After protein extraction and tryptic digestion, three to four selected marker peptides for each grain species were measured by HPLC-MS/MS. Emulsion-type sausages with grain-based protein concentrations in the range of 5–1000 mg/kg and blank values were produced. The limits of detection of the method were ≤5 or ≤10 mg grain protein/kg meat product for each grain species and no false-positive or -negative results were obtained. The detectability of the marker peptides only slightly decreased after storage and grilling of sausages, whereas the influence of the canning process was noticeably higher.
The contents of the 15+1 EU priority PAH were analysed from 113 representative commercial smoked German meat products collected in the year 2006 with a Fast-GC/HRMS method. The median of benzoapyrene ...content was 0.03 μg/kg and therefore greater than a factor of 100 below the maximum level of 5 μg/kg. The highest content of benzoapyrene was detected in a Frankfurter-type sausage (0.43 μg/kg). The sum content of benzoapyrene, benzoaanthracene, chrysene and benzobfluoranthene (“PAH4”), as proposed by the European Food Safety Authority to be a good marker for PAH in food, was 0.28 μg/kg in median, and the sum content of the 15+1 EU priority PAH was 0.64 μg/kg in median. The analysed smoked meat products showed an increasing presence of PAH in the following order: cooked ham (n = 17) < raw sausages (n = 25) < liver sausages (n = 25) < raw ham (n = 23) < Frankfurter-type sausages (n = 23). The correlation coefficient (R) between BaP and the sum of the 15+1 EU priority PAH was 0.90. To increase the safety of the consumer, a lowering of the BaP maximum level to 1 μg/kg is proposed and critical aspects using “PAH4” as a marker for PAH in food surveillance are discussed.
Food fraud is a common issue in the modern food industry. The undeclared use of foreign proteins in meat products is a major concern in this context. Oilseeds are ideal for this purpose due to their ...high protein content and since huge amounts of oil meal are obtained as a by-product of oil production. Therefore, a UHPLC-MS/MS method was developed for the simultaneous detection of chia, coconut, flaxseed, hemp, peanut, pumpkin, rapeseed, sesame, soy, and sunflower proteins in meat products. Potential tryptic peptide markers were identified by high-resolution mass spectrometry. The final twenty peptide markers selected, which are specific for one of the ten species targeted, were each measured by multiple reaction monitoring. To the best of our knowledge, twelve new heat-stable marker peptides for chia, coconut, flaxseed, pumpkin, rapeseed, sesame and sunflower have not been reported previously. Emulsion-type sausages with 0.01, 0.25, 0.50, 0.75 and 1.00% protein addition by each oilseed species were produced for matrix calibration. No false-positive results were recorded. In the quantification of the ten oilseed species, 466 of 480 measuring data points of the recovery rate in unknown sausages (0.15 and 0.85% protein addition by each oilseed species) were in the accepted range of 80–120%.
The contents of polycyclic aromatic hydrocarbons (PAH) and phenolic substances in Frankfurter-type sausages were investigated depending on hot smoking conditions (glow smoke). For the 24 smoking ...experiments (performed in duplicates) three different smoke densities and ventilator velocities as well as wood chips with five different moisture contents were tested. During the smoking process, concentrations of O2, CO2 and CO, humidity and temperature in the smoking chamber as well as smoke generation temperature were determined. The chemical analysis included the contents of the 15+1 EU priority PAH and the phenolic substances guaiacol, 4-methylguaiacol, syringol, eugenol and trans-isoeugenol. The smoking conditions had a significant influence on smoke generation temperature, organoleptic properties and the formation of PAH and phenolic substances. The PAH contents increased with smoke density and ventilator velocity. No correlation between the contents of PAH and phenols was observed.
► A decrease of smoke generation temperature leads to low PAH contents. ► Smoking conditions notably influence the formation of PAH and phenolic substances. ► The PAH contents ascend due to an increase in smoke density and ventilator velocity. ► Lowering PAH contents does not necessarily lower contents of phenolic substances. ► An increase in moisture of wood chips does not automatically decrease PAH contents.
Meat substitution by legume proteins in various types of meat products is a common practice. A reliable detection and quantification of these additives is required to control food specifications, ...especially regarding food fraud. Consequently, a UHPLC-MS/MS method for the simultaneous detection of alfalfa (
), broad bean (
), chickpea (
), lentil (
), lupine (
and
), pea (
), peanut (
), and soy (
) proteins in meat products was developed. After protein extraction and tryptic digestion, three marker peptides for each legume species were measured by multiple reaction monitoring (MRM) using an optimized extraction protocol. To the best of our knowledge, the marker peptides for alfalfa, broad bean, chickpea, and lentil have not been reported previously. Emulsion-type sausages with 0.1, 0.4, 0.7, 1.0, 1.3, 1.6, 1.9, 2.2, and 2.5% meat substitution by each legume species, representing the concentration range between inadvertently transferred cross-contaminations and the conscious use for meat substitution, were produced for matrix calibration. No false-positive results were recorded in blank samples. In the quantification of alfalfa, broad bean, chickpea, lentil, pea, peanut, and soy, 673 of 756 measuring data of the recovery rate in unknown sausages were in the accepted range of 80-120%.
A GC/MS method for the determination of ten polycyclic aromatic hydrocarbons (PAH) with four to six condensed aromatic carbon rings (including the six carcinogenic PAH) in smoked meat products and ...liquid smokes has been developed. The method implies accelerated solvent extraction (ASE), gel permeation chromatography for efficient lipid removal without saponification and ^sup 13^C-labelled PAH for quantification. The calibration curves showed a good linearity for all PAH in the concentration range 0.01-10,000 ppb, the repeatabilities (RSDs, n=6) of different PAH ranged from 3 to 12%. Using this method, the analysis of a standard reference material of the National Institute of Standards and Technology (mussel tissue, SRM 2977) resulted in a good accordance between measured and certified PAH concentrations. The determination of PAH contents in 26 samples of smoked meat products and liquid smokes further confirmed the analytical power of the new method and gave a first insight into the specific PAH patterns.PUBLICATION ABSTRACT
The contents of eight oxygenated polycyclic aromatic hydrocarbons (OPAHs; anthracene-9,10-dione, benzoaanthracene-7,12-dione, 11H-benzobfluorene-11-one, 6H-benzocdpyren-6-one, ...7H-benzodeanthracene-7-one, 9,10-dihydro-8H-benzoapyren-7-one, fluoren-9-one, and naphthacene-5,12-dione) and six PAHs (anthracene, fluorene, and PAH4) were investigated in barbecued meat and non-meat patties. The patties were prepared with ten setups (six replicates, each) of barbecue conditions defined by grill type, grate height, heating medium, and barbecue time. The highest median contents were observed with a disposable grill (OPAHs: 46.3 µg/kg; PAHs: 40.7 µg/kg) and a charcoal grill (OPAHs: 29.6 µg/kg; PAHs: 23.3 µg/kg). Fluoren-9-one and anthracene-9,10-dione were the dominant compounds within OPAHs, but also the four toxicologically most relevant OPAHs were detected with a total up to 11.8 µg/kg. Pairs of OPAHs and corresponding PAHs did not show strong correlations, as individual OPAHs and PAHs were affected differently by the barbecue conditions. No suitable markers for OPAH prediction could be found. We recommend to include OPAHs in future PAH investigations.
Microbial transglutaminase (TG) is an enzyme isolated on an industrial scale from
Streptomyces mobaraensis
. Technical TG, a formulated powder, is primarily used to restructure meat in the ...meat-processing industry, typically at a 1% concentration and is often referred to as “meat glue.” In the European Union, meat restructured with TG requires the indication “formed meat” on the label according to Regulation (EU) No 1169/2011. In order to detect food fraud like the undeclared TG usage in meat and meat products, a qualitative mass spectrometric method using specific tryptic marker peptides has been published in 2017. Here the successful inter-laboratory validation and first-time standardization of a proteomics method for food control is described, which was subsequently included into the Official Collection of Analysis Methods according to the German Food and Feed Code (§ 64 LFGB). Thirteen laboratories from governmental, academic, and private institutions participated in the study, whereas four laboratories did not meet the minimal quality criteria and therefore their results had to be excluded. Three different test materials containing between 0.2 and 2% technical TG as well as blank samples were produced and tested. The laboratories used triple-quadrupole mass spectrometers from several vendors as well as quadrupole time-of-flight instruments. The detection of TG was considered to be positive, if three mass transitions for the marker peptides VTPPAEPLDR (TG-1) and SPFYSALR (TG-2), each, showed a signal-to-noise ratio of at least 3. The level of detection LOD
95%
for the median laboratory with intermediate performance was 0.31%, the false-positive rate was 0% and the false-negative rate was 2.1%.
Meat products are susceptible to food fraud due to their high commercial value. One possible adulteration is the undeclared substitution of high-priced meat protein by cheaper foreign proteins. A ...reliable detection of these added proteins is required in order to control food specification, especially regarding food fraud. A sensitive multi-method for the detection of 23 foreign protein sources (alfalfa, buckwheat, broad bean, chia, chickpea, coconut, egg, flaxseed, hemp, lentil, lupine blue, maize, milk, pea, peanut, potato, pumpkin, rapeseed, rice, sesame, sunflower, soy, and wheat) in meat products applying high performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS) has been developed. In this context, a new rapid defatting procedure, without carry-over effect, suitable for routine analysis, a robust protein extraction protocol (TRIS/HCl (1 M, pH 8.2) with 40% acetonitrile), suitable for various animal- and plant-based proteins including grain proteins, and new peptide markers for buckwheat and potato were established. A comprehensive investigation of the influence of cooking (emulsion-type sausages), grilling (hamburger patties) and maturation (salamis) showed that the detection method is robust against different types of processing. The limits of detection for all foreign protein sources were ≤ 0.02% protein and no false-positive or -negative results were obtained.
•Simultaneous detection of 23 foreign protein sources in meat products.•Identification of new heat-stable peptide markers for buckwheat and potato.•Establishment of a robust extraction protocol for various foreign proteins.•Development of a new rapid defatting procedure for meat products without carry-over.•Method is suitable for differently processed meat products.
The fraudulent substitution of high-quality with lower priced poultry meat is quite conceivable and consumers’ concerns have been reported previously. A reliable authentication of the poultry species ...is required to control specifications. Consequently, an HPLC-MS/MS method for the simultaneous detection of chicken, duck, goose, guinea fowl, ostrich, pheasant, pigeon, quail and turkey in raw and heated meat was developed. Potential marker peptides were identified by a shotgun proteomic approach (HPLC-QToF-MS/MS) after protein extraction followed by tryptic digestion, testing different conditions for extraction in order to extract a broad spectrum of proteins from each species. The final twenty-eight marker peptides selected, which are specific for one of the nine targeted species each, and one common turkey/chicken peptide were measured by multiple reaction monitoring (MRM) using an optimized extraction protocol. To the best of our knowledge, twenty-three of these marker peptides have not been reported previously. The suitability of the marker peptides was verified by the analysis of 42 different poultry samples from the nine species included in this study. All twenty-nine marker peptides were heat stable.
•Characteristic tryptic marker peptides for nine poultry species were identified.•The identified marker peptides were heat stable and unaffected by meat processing.•The extraction of the marker peptides' target proteins was optimized.•The suitability of the method was verified by analyzing commercial poultry samples.•The substitution of high-quality with lower priced poultry meat can be detected.
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